Memory leak when disabling help

You only erase the command from the list, but don't delete it. Potential fix:

		void disable_help() {
			for (auto command = _commands.begin(); command != _commands.end(); ++command) {
				if ((*command)->name == "h" && (*command)->alternative == "--help") {
					delete  *command;
					_commands.erase(command);
					break;
				}
			}
		}